| 摘要 |
PROBLEM TO BE SOLVED: To provide a grid-connection device that synchronizes a grid voltage and the carrier of a power conversion device at high speed, prevents the occurrence of noise and higher harmonics due to a variation of a carrier frequency, and improves the stability of control.SOLUTION: A grid-connection device includes: third harmonic waveform data generating means 32 for generating third harmonic waveform data Sby using a positive phase of a three-phase grid voltage as a reference waveform; a third harmonic table 33 for generating third harmonic waveform data Ssynchronized with a carrier frequency; a coordinate converter 25 for detecting the phase difference &Dgr;Φ between the third harmonic waveform data Sgenerated by the third harmonic waveform data generating means 32 and the third harmonic waveform data Sgenerated by the third harmonic table 33; a synchronization controller 26 for adjusting the carrier frequency so that the phase difference &Dgr;Φ is zero; and a carrier-frequency generating circuit 27. This configuration synchronizes the grid voltage with the carrier of the power conversion device at high speed when a power conversion device is reset and is connected to the grid at the time of restoration of power. |
